package com.wzbc.video.utils;

import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;
import java.util.Random;

public class FileUtil {
    public static String base_url = "C:/Users/DXC/IdeaProjects/video-back/static/";

    public static String saveFile(MultipartFile file, String path,String name) {
        if (file.isEmpty()) {
            return "empty";
        }
        String originalFilename = file.getOriginalFilename();
        String fileExtName = originalFilename.substring(originalFilename.lastIndexOf(".") + 1);
        String filePath = base_url.concat(path).concat("/");
        File temp = new File(filePath);
        if (!temp.exists()) {
            temp.mkdirs();
        }
        File localFile =null;
        Random random = new Random();
        String filename = null;
        String url = null;
        do {
            filename = name.concat("_").concat(String.valueOf(random.nextInt(7)).toString());
            url=filePath.concat(filename).concat(".").concat(fileExtName);
            localFile = new File(url);
        }while(localFile.exists());
        try {
            file.transferTo(localFile); //把上传的文件保存至本地
        } catch (IOException e) {
            e.printStackTrace();
            return "bad";
        }
        return url;
    }

    public static OutputStream download(String path, HttpServletResponse response) {
        try {
            // path是指想要下载的文件的路径
            File file = new File(path);
            // 获取文件名
            String filename = file.getName();
            // 获取文件后缀名
            String ext = filename.substring(filename.lastIndexOf(".") + 1).toLowerCase();

            // 将文件写入输入流
            FileInputStream fileInputStream = new FileInputStream(file);
            InputStream fis = new BufferedInputStream(fileInputStream);
            byte[] buffer = new byte[fis.available()];
            fis.read(buffer);
            fis.close();

            // 清空response
            response.reset();
            // 设置response的Header
            response.setCharacterEncoding("UTF-8");
            //Content-Disposition的作用：告知浏览器以何种方式显示响应返回的文件，用浏览器打开还是以附件的形式下载到本地保存
            //attachment表示以附件方式下载   inline表示在线打开   "Content-Disposition: inline; filename=文件名.mp3"
            // filename表示文件的默认名称，因为网络传输只支持URL编码的相关支付，因此需要将文件名URL编码后进行传输,前端收到后需要反编码才能获取到真正的名称
            response.addHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(filename, "UTF-8"));
            // 告知浏览器文件的大小
            response.addHeader("Content-Length", "" + file.length());
            OutputStream outputStream = new BufferedOutputStream(response.getOutputStream());
            response.setContentType("application/octet-stream");
            System.out.println("下载开始");
            outputStream.write(buffer);
            System.out.println("下载结束");
            return outputStream;
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        return null;
    }
}
